Recording pen check mechanism



June 13, 1950 F. s. BUHRENDORF EI'AL 2,571,195

RECORDING PEN cmcxm-zcnmxsm Filed April 50, 1948 3 Sheets-Sheet 1INVENTORS ggg 'gxgRF AT TORNEY June 950 F. G. BUHREN-DORF ETAL 5 3RECQRDING PEN CHECK MECHANISM Filed April 30, 1948 I 3 Sheets-Sheet 2 F.G. BUHRENDORF INVENTORS EDERMOND A T TOR/VEY June 1950 F. e. BUHRENDORFETAL 2,511,195 7 RECORDING PEN CHECK MECHANISM I 3 Sheets-Sheet 3 FiledApril 50, 1948 F. G. BUHRENDORF INVENTORS F DERMOND A T TORNE Y PatentedJune 13, 1950 UNITED STATES PATENT OFFICE RECORDING PEN CHECK MECHANISMNew York Application April 30, 1948, Serial No. 24,214

Claims. 1

This invention relates to mechanism for protecting a delicate instrumentfrom injury due to forcible contact with a surface and is particularlyuseful in recording machines.

The object of the invention is a selective latching device which, whenthe instrument is dropped or forced down, will prevent the instrumentfrom coming in contact with the surface; but, when the instrument islowered gently, will permit the instrument to come into contact with thesurface.

A feature of the invention is a bracket pivoted to the recordingcarriage and carrying the recording instrument. A spring extendingbetween the recording carriage and the bracket tends to rotate thebracket and bring the instrument into contact with the surface.

Another feature of the invention is a pawl pivoted to the carriage andextending between two studs on the bracket, so that the pawl will beraised by one of the studs when the bracket is rotated to raise theinstrument from the surface. When the bracket is freely released, orforced down, a projection on the pawl engages the other stud preventingthe instrument from coming into contact with the surface; but, when thebracket is lowered slowly, the projection on the pawl passes the otherstud, permitting the instrument to come into contact with the surface.

In the drawings:

Fig. 1 is a side view of the carriage, bracket and instrument;

Fig. 2 is a front view of the rails, carriage, bracket and instrument;

Fig. 3 is a top view of Fig. 2;

Fig. 4 is a detail view, in part section, of the carriage, bracket andpawl when the instrument is in contact with the surface;

Fig. 5 is a detail view, in part section, of the carriage, bracket andpawl when the instrument is fully raised from the surface;

Fig. 6 is a detail view, in part section, of the carriage, bracket andpawl when the pawl is engaged with one of the studs to prevent thebracket from rotating to bring the instrument into contact with thesurface;

Fig. 7 is a detail view, in part section, of a. preferred means forsecuring a specific type of instrument to the bracket; and

Fig. 8 is a general view of the complete carriage, traversing mechanismand recording surface.

The rails I, 2 may be mounted in, or supported by, any suitable part(not shown) of the frame- CIA work of the recorder, or of asubframework. The 66 pen carriage 3 may be slidably mounted upon therails I, 2, and may be traversed in accordance with the values to berecorded by any suitable means, symbolically represented by the rack 4,traversed by the gear 5 on the shaft of the servomotor 6, rotatedproportionally to the values to be recorded. The present invention isnot limited to the specific form of drive illustrated, which may bereplaced by many other known forms of drive, such as a pulley on theshaft of the motor driving a cable attached to the pen carriage, athreaded shaft driven by the motor and driving a nut attached to the pencarriage, or any other suitable device. If desired, the pen carriage maybe stationary and the record surface 25 may be moved laterally inaccordance with the values to be recorded.

The pen bracket I depends from the pen carriage 3, on the pivot 8, andstub shaft 9, shown most clearly in Figs. 2 and 3. A portion of theshaft 9 may be reduced in diameter to form a shoulder bearing againstthe bracket l, and be secured in any suitable way, as by staking,rivetins, or by the nut II. The outer end of shaft 9 protrudes through ahole in the carriage 3 and may be secured by the collar and set screwI0. In this way, by loosening the collar I0, the pen bracket 1 may beadjusted laterally with respect to the carriage 3, then retained by thecollar and set screw I0.

One end of a spring I2 is inserted in a hole in the carriage 3, thespring is coiled round the inner end of the pivot 8, and the other endof the spring rests in a notch cut in the bracket 1. The spring I2 istensioned so as to tend to rotate the bracket I to the recordingposition.

Any suitable type of recording device may be mounted upon the bracket 1.In the present case, a suitable form of mounting for a commerclal typeof ball point pen is illustrated, but the invention is not limited tothis specific recording device. An internally threaded socket I3projects through a hole in the bracket I and is shaped to form ashoulder abutting against the outer face of the bracket I, and a cornerwhich is securely staked to the inner face of the bracket I. A tube I4,closed at the upper end by the perforated cap I5 is slipped over theprojecting end of the socket I3. A spacer I6 and plate I! are slippedover the tube I 4. A fiat spring I8 and clamp plate I9 are placed on topand the whole assembly screwed to the bracket I. The pen 20 is slippedinto the socket I3 until the thread on the barrel of the pen 20 engagesthe internal thread of the socket I3 and is then screwed securely inplace. The fiat spring i 8 is shaped to engage the rail i and hold thebracket 1 when the pen 2B is fully rotated away from the recordingsurface.

A pawl 2| is mounted upon a headed rivet 22 riveted in a hole in thecarriage 3. A spacer (not shown) may be placed between the pawl 2| andcarriage 3 to insure free rotation of the pawl. A stud 23 is riveted inthe bracket '1 and engages the lower surface of the pawl H. A spur isformed on the upper surface of the pawl 2| and a stud 24 is riveted inthe bracket 1. The carriage 3 is cut away to permit the full movement ofthe stud 2%.

Fig. 5 shows the relative positions of the parts when the bracket i isfully rotated to lift the pen from the recording surface, the spring I8is fully engaged with the rail L the spring [2 is fully compressed, andthe stud 23 has raised the pawl Z: to its upper position.

If the movement of the pen is retarded, so as to lower the pen gentlyinto contact with the recording surface, the pawl 2! will continuouslybe in contact with the stud 23, and the spur on the pawl 2| will justclear the stud 24, as shown in Fig. 4.

If the pen is forced down from the position shown in Fig. 5, orpermitted to move under the impulse of the spring l2, the bracket 1 willrotate faster than the pawl 2!, thus, as shown in Fig. 6, the pawl 2|will lose contact with the stud 23, and the spur on the pawl 21 willengage the stud 24, preventing the pen from coming in contact with therecording surface, thus protecting the point of the pen.

While the elements 23, 24 have been illustrated as studs riveted to thebracket 1, it is evident that any suitabiy shaped projections, orabutments, may be used, such as small tongues of metal punched out ofthe bracket 1; or the bracket '2 may be shaped to present a surface tothe pawl 21, pierced by an aperture so disposed that the lower edge ofthe aperture replaces the stud 23, and the upper edge of the aperturereplaces the stud 24.

The selective latching action of the pawl 2! results from the bracket'1, when freely released, having a higher rotational or angular velocitythan the angular velocity of the pawl 2|. In

the present case, the recoil of the spring !2' causes the bracket '1 tohave a higher angular velocity than the pawl 21, but there evidently areother ways in which this difference in velocity may be attained. Forexample, if the spring i2 be omitted and the bracket 1 be permitted toturn freely under the influence of gravity, a disc of friction materialmay-be associated with the pawl 2! so that the pawl 2|, under theinfluence of gravity, will rotate with lower angular velocity than thebracket '1.

What is claimed is:

1. Mechanism for protecting a. delicate instrument from injury due toforcible contact with the surface of a member comprising a supportadjacent to the surface, a bracket attached to the instrument andpivoted to depend from the support, said bracket being shaped to formtwo abutments, a pawl pivoted to said support and having a lower surfacecapable of bearing upon one of said abutments and an upper surfaceshaped to form a projection, and means associated with the pivotedsupports of said bracket and said pawl, so proportioned that, whenfreely released, said bracket will rotate faster than said pawl, wherebythe projection on the pawl is caused to engage the other of saidabutments and prevent said instrument from coming in contact with saidsurface.

2. The combination in claim 1 in which said means is a spring extendingfrom said support to said bracket and exerting pressure on said bracket.

3. Mechanism for protecting a recording instrument from injury due toforcible contact with a recording surface comprising a support adjacentto the recording surface, a bracket attached to the recording instrumentand pivoted to depend from the support, the bracket being shaped to formtwo abutments, a pawl pivoted to the support and having a lower surfacehearing on one of said abutments and an upper surface shaped to form a,projection and means associated with the bracket and pawl soproportioned that, when freely released from an elevated pb's'ition, thebracket will rotate faster than the pawl, causing the pawl to rise fromsaid one abutment whereby the projection on the pawl is brought intoengagement with the other abutment preventing the recording instrumentfrom coming in contact with the recording surface.

4. The combination in claim 3 in which said means is a, spring extendingfrom the support to the bracket and exerting pressure on the bracket.

5. In a recording machine, a recording surface, a recording carriageslidably supported adjacent to said surface, a bracket pivoted to dependfrom the carriage, a, pair of studs secured to said bracket, a recordingdevice attached to said bracket, a spring extending from the carriage tothe bracket and exerting pressure on the bracket, a pawl pivoted to thecarriage and extending between the studs, said pawl having a projectionformed to engage one of said studs when said recording device is freelyreleased from an elevated position to prevent the recording device fromcoming in contact with the recording surface.

FREDERICK G. BUHRENDORF. FRANKLIN DERMOND.

Number Name Date 2,424,776 Stapleton July 29, 1947 2,426,301

Ellis et a1 Aug. 26, 19%?

